Honda Accord Crosstour Tire and Wheel Questions

I got a terrible flat in one of my tires on my Subaru Tribeca, and I was told that if the thread difference was greater than some number, I'd need to replace all 4 tires, or it would destroy the transmission.

On an Accord Crosstour AWD, can just one tire be replace (or at worst case, 2),

or, do you need to replace all 4 tires if the remaining thread difference is too great?

What's bad about not replacing the entire set if the tires are worn is that the new tire will have a larger circumference. To illustrate, imagine a simple axle with two different sized tires on either end. If you roll the assembly in a straight line, the smaller tire will want to make more rotations to travel the same distance as the larger (new, less worn) tire. NOT good for what lies in between.

A friend of mine owns a tire shop/garage and he won't replace one tire for someone with an AWD vehicle because you KNOW that when something happened to the car, the customer would come back on him. They've even shaved tread off of a new tire to match the circumference with the rest of the set.